1. Field of the Invention
The present invention involves a chuck wrench with a safety device incorporated therewith, and further may include a bypass button that permits the safety device to be temporarily deactivated during use.
2. Description of the Related Art
Chuck wrenches are well known as keys for adjusting the chuck on a machine tool, among other things. Chuck wrenches of various shapes and sizes exist, from the small key used to change a hand held electric drill to a large, heavy wrench to tighten and loosen the chuck on a massive machine tool. A chuck wrench for a machine tool can weigh a pound or more and typically comprises a high content of metal.
The chuck, when the machine tool is turned on, can accelerate to speeds of two thousand revolutions per minute from a dead rest relatively quickly. In the event a machine tool operator, either through neglect, inexperience or otherwise, fails to remove a chuck wrench prior to activating the machine tool, the chuck wrench can become a hazardous, high-speed projectile once the machine tool is turned on. This, quite obviously, is an undesirable and unsafe working environment, and others have sought to prevent this occupational danger through various means.
U.S. Pat. No. 2,588,565 (the '565 patent) describes a safety lock incorporated onto a machine tool that prevents the controlling switch from being activated until a chuck wrench is placed in the lock. This is disadvantageous for multiple reasons. An existing machine tool would have to be retrofitted with this particular safety lock, which can be expensive if even practical. This safety lock may also not be compatible with more than one type of chuck wrench. Alternatively, a negligent operator who views the safety device as an annoyance may simply keep a spare chuck wrench or some other item of sufficient weight in the lock to intentionally bypass the safety lock and thereby eliminate its efficacy.
Somewhat similar to the '565 Patent, U.S. Pat. No. 7,335,840 (the '840 patent) describes a safety apparatus incorporated onto a machine tool, where the apparatus includes an actuator switch connected to the circuits of the machine tool such that, when the chuck wrench is placed in the apparatus, the machine tool cannot be activated. The '840 patent has the same disadvantages as those of the '565 patent, except that the safety apparatus of the '840 patent further requires electrical work to be performed in order to retrofit an existing machine.
U.S. Pat. No. 3,673,895 (the '895 patent) discloses a chuck wrench that includes a spring to create a self-ejecting mechanism. This spring forces the chuck wrench away from the machine tool chuck, such that, when the operator has completed using the chuck wrench, in the event the operator leaves the chuck wrench in the machine tool, the force of the spring would push the chuck wrench out of the chuck. This type of chuck wrench also has significant disadvantages. The operator is not only required to exert torque force on the chuck wrench while turning it to tighten the chuck, but also must exert downward force on the chuck wrench, in the direction of the chuck, to counteract the opposing forces created by the spring. Alternatively, the operator may readily remove or otherwise disable the spring so as to intentionally bypass the safety mechanism and thereby eliminate its efficacy.
Rather similar to the '895 patent, U.S. Pat. No. 3,869,943 (the '943 patent) also discloses a chuck wrench with a self-ejecting spring, having the same disadvantages as the '895 patent.
U.S. Pat. No. 2,618,995 (the '995 patent) discloses a chuck wrench with an internal spring, where the spring does not push the chuck wrench as a whole away from the machine tool chuck, but instead retracts a portion of the wrench that engages the chuck back into the wrench. This type of chuck wrench also has significant disadvantages, similar to those of the '895 and '943 patents.